An iOS developer named Mario Ciabarra have released a patch namely WiFried and it's currently available on Cydia app store.
Of course the app is designed to deal with the existing issues on Wifi that is now attacking iOS 8 / 8.1 users. With it you can enable or disable AWDL / AirDrop support with a single tap, because this is considered the culprit of Wifi problem.
I’ve narrowed down the issue to the use of Apple’s Wireless Direct Link (AWDL) that is used for AirDrop, AirPlay, and Gaming connections.And the following is an instructions you can perform to install WiFried package from Cydia to fix the Wifi issue on iOS 8.
I’ll go out on a limb and say the WiFi issues are because of Apple’s choice of using Bonjour over AWDL and that, given the constraints of the WiFi hardware, this will be difficult to get right.
Step 1. On your jailbreak iOS device now launch Cydia.
Step 2. Tap the available Search button on tab bar to search WiFried.
Step 3. When WiFried appears, then tap to install and make a confirmation on installing the package on your iOS 8 based iPhone.
Step 4. You need to disable AWDL to get rid off Wifi issue, just swipe up from button of your screen to launch Control Center, tap on AirDrop now, select Once found, open it and tap on Install -> Confirm to install the package on your iOS 8 device.WiFried (AWDL Off).
Step 5. Done.
Surprisingly this issue also appears on OS X Yosemite, if you are a user of the said OS to fix the Wi-Fi network issue just type the terminal commands on your desktop.
sudo ifconfig awdl0 downNow if you wish to enable AWDL again, just type the command below.
sudo ifconfig awdl0 upHope the above mentioned solutions work for you. And your Wifi works again like it used to. Good luck.